DE102015216343A1 - Anode-cathode supply - Google Patents

Abstract

The invention relates to an anode-cathode supply device (20, 30) for a fuel cell of a fuel cell system with an anode supply (20) and a cathode supply (30), which by means of an interposed overflow line (100/200 / ...) and by a Overflow valve (400) through each other in a fluid communication can be brought, wherein the spill valve (400) as an NC spill valve (400) is formed, wherein in a de-energized state of the NC overflow valve (400) and at a balanced pressure ratio at the NC spill valve (400) the NC overflow valve (400) is closed. Furthermore, the invention relates to a method for supplying or a device for supplying an operating medium (3), in particular hydrogen (3), from an anode to a cathode of a fuel cell (10) of a fuel cell system (1), preferably a vehicle, in particular an electric vehicle , temporally at and / or in time after a shutdown of the fuel cell (10). Moreover, the invention relates to a fuel cell system (1) for a vehicle, in particular an electric vehicle, or a vehicle, in particular electric vehicle.

Description

The invention relates to an anode-cathode supply device for a fuel cell of a fuel cell system of a vehicle, in particular of an electric vehicle. Furthermore, the invention relates to a method for supplying or a device for supplying an operating medium, in particular hydrogen, from an anode to a cathode of a fuel cell of a fuel cell system, preferably a vehicle, in particular an electric vehicle, in time and / or in time after a shutdown of the fuel cell , Moreover, the invention relates to a fuel cell system for a vehicle, in particular an electric vehicle, or a vehicle, in particular an electric vehicle.

A fuel cell uses a chemical reaction of a fuel with oxygen to water to generate electrical energy. For this purpose, the fuel cell contains as a core component at least one so-called membrane electrode assembly (MEA for Membrane Electrode Assembly), which is a microstructure of an ion-conducting, often proton-conducting, membrane and on both sides of the membrane arranged electrodes, an anode and a cathode , In addition, gas diffusion layers (GDL) can be arranged on both sides of the membrane-electrode assembly on the sides of the electrodes facing away from the membrane.

In general, the fuel cell is formed by a plurality of stacked in a stack (English stack) membrane electrode assemblies, wherein add their electrical power in an operation of the fuel cell. Bipolar plates, also called flux field plates, are generally arranged between the individual membrane-electrode units, which ensure supply of the membrane-electrode units, that is to say the individual cells of the fuel cell, with the operating media, the so-called reactants, and usually also a cooling serve. In addition, the bipolar plates provide an electrically conductive contact to the membrane-electrode assemblies.

In an operation of a single cell, the fuel, a so-called anode operating medium, in particular hydrogen (H ₂ ) or a hydrogen-containing gas mixture, is supplied via an anode-side open flow field to the bipolar plates of the anode, where an electrochemical oxidation of H ₂ to 2H ⁺ under a release of electrons (2e ^- ) takes place. Through a membrane or an electrolyte through which separates the reaction spaces gas-tight from each other and electrically isolated, takes place a water-bound or anhydrous transport of protons (H ⁺ ) from an anode compartment out into a cathode compartment. The electrons provided at the anode are fed via an electrical line and an electrical load (electric motor) of the cathode.

The cathode is supplied via a cathode side open flow field of the bipolar plates, a so-called cathode operating medium, in particular oxygen (O ₂ ) or an oxygen-containing gas mixture, for example air, so that a reduction of O ₂ to 2O ^2- takes place under a recording of electrons. At the same time, oxygen anions (O ^2- ) formed in the cathode space react with the protons transported through the membrane to form water.

In order to supply a fuel cell stack, hereinafter also referred to as fuel cell, with operating media, it has, on the one hand, an anode supply and, on the other hand, a cathode supply. The anode supply has an anode supply path for supplying the anode operating medium into the anode chambers of the fuel cell and an anode exhaust path for discharging an anode exhaust from the anode chambers. Analogously, the cathode supply has a cathode supply path for supplying the cathode operating medium into the cathode chambers of the fuel cell and a cathode exhaust gas path for discharging a cathode exhaust gas out of the cathode chambers.

The following statements refer to the in the 2 and 3 illustrated prior art. In the cathode supply 30 can the cathode of the fuel cell 10 by means of a shut-off valve 310 in the cathode supply path 31 and by means of a shut-off valve 320 in the cathode exhaust path 32 from an environment 2 be separated fluid mechanically. The anode supply 20 and the cathode supply 30 are also by means of a purge valve (English) and a Abscheiderventils in corresponding lines between the anode supply 20 and the cathode supply 30 fluidmechanically connectable.

It is in the 2 the separator valve 401 as a NO overflow valve 401 - English NO for Normally Open, so an overflow valve, which is open when it is not energized or driven, that is, for example, that the fuel cell is turned off - designed to be switched off with the fuel cell system 1 a critical overpressure or a critical pressure difference between the anode and the cathode of the fuel cell 10 to avoid. In addition, by means of the NO overflow valve 401 Hydrogen to the cathode for protection against harmful air-air starts of the fuel cell 10 guided.

Another possibility in the prior art to avoid a critical overpressure is the bleed valve 401 as a NO overflow valve 401 to do something in the 3 is shown, and a pressure equalization and a supply of hydrogen to the cathode via the NO spill valve 401 to enable. The problem with these two solutions is that when and after a shutdown of the fuel cell, a hydrogen in the fluid-mechanically shut off part of the fuel cell between the anode and the cathode is not homogeneously distributed, since a flow of hydrogen almost exclusively through the corresponding open valve and not over the membrane of the fuel cell takes place.

The DE 10 2006 035 851 B4 discloses a fuel cell system having an anode supply path and a cathode supply path for supplying a fuel cell with hydrogen and air. Furthermore, the fuel cell system has an anode exhaust path and a cathode exhaust path. The cathode supply path is fluidly communicable with the anode supply path via a conduit and an air supply valve located in the conduit. The air supply valve is opened for an anode purging process, so that cathode-side air can reach an anode side of the fuel cell. If no anode rinsing process takes place, the air supply valve is pressure-independent closed.

The invention has for its object to be able to safely operate a fuel cell of a fuel cell system without the fuel cell tends to air-air starts. This should be feasible with simple means, wherein during and after switching off the fuel cell, hydrogen should be distributed homogeneously in a fluid-mechanically shut-off part of the fuel cell between an anode and a cathode of the fuel cell. In this case, no critical pressure differences between the anode and the cathode may occur.

The object of the invention is by means of an anode-cathode supply device for a fuel cell of a fuel cell system preferably by a method for supplying an operating medium by means of a fuel cell system for a vehicle, in particular an electric vehicle, and / or by means of a vehicle, in particular an electric vehicle, according to the independent Claims solved. Advantageous developments, additional features and / or advantages of the invention will become apparent from the dependent claims and the following description.

The anode-cathode supply device according to the invention comprises an anode supply and a cathode supply, which can be brought into fluid communication with one another by means of an overflow line arranged therebetween and through an overflow valve, and the overflow valve is designed as an NC overflow valve, that is to say in a non-energized, that is a non-driven, state of the NC overflow valve and a balanced pressure ratio at the NC overflow valve, the NC overflow valve is closed. The term "NC overflow valve" or "NC valve" refers to a normally closed valve (English: normally closed).

This also preferably means that the NC overflow valve closes (closing pressure difference) and / or closes at a pressure difference applied to the NC overflow valve which is (clearly) below (uncritical pressure difference) a critical pressure difference between the anode supply and the cathode supply for the fuel cell , The fuel cell itself is turned off or just turned off. Furthermore, the overflow valve is located on or in the overflow line.

In exemplary embodiments, the NC overflow valve is designed such that the NC overflow valve opens at a pressure difference at the NC overflow valve (opening pressure difference), which is below or slightly below a critical pressure difference between the anode supply and the cathode supply for the fuel cell. In exemplary embodiments, the (uncritical) pressure difference at which the NC overflow valve opens at the earliest (opening pressure difference) is about 97.5%, about 95%, about 92.5%, about 90%, about 85%, about 80%, about 75%, about 70%, about 65%, about 60% or about 50% ± 1-2% of the critical pressure difference.

The closing pressure difference is in each case preferably slightly below that, ie the opening pressure difference of the overflow valve is slightly greater than or equal to the closing pressure difference of the overflow valve. In general, the critical pressure difference is greater than or slightly greater than the opening pressure differential, which in turn is slightly greater than or substantially equal to the closing pressure differential, the closing pressure differential being zero (fluid over pressure at the cathode or no fluid overpressure) and below (Fluid pressure at the anode) can go.

In embodiments, the NC spill valve is configured such that the NC spill valve opens at an anode-side fluid pressure that is above a cathode-side fluid pressure, with a pressure difference between the anode-side fluid pressure and the cathode-side fluid pressure below or below is below the critical pressure difference for the fuel cell.

That is, as the pressure difference (opening pressure difference) on the NC spill valve approaches the critical pressure difference, fluid flows through the overflow line and the spill valve from the anode supply to the cathode supply, thus producing at least partial pressure equalization. An uncritical pressure difference on the fuel cell which can be achieved thereby, or the closing pressure difference between the anode supply and the cathode supply, is preferably well below the critical pressure difference for the fuel cell. Again, the above-mentioned values for the uncritical pressure difference or the closing pressure difference, such as 75% of the critical pressure difference, between the anode supply and the cathode supply are again applicable.

In exemplary embodiments, the overflow line is furthermore designed as a separator line, a rinse line or another line, wherein the overflow line opens into the anode supply and into the cathode supply. Such an overflow line may also be referred to as an outflow line. Furthermore, in exemplary embodiments, the overflow line is provided in such a way that it opens into the cathode supply within a region of the cathode supply that is fluid-mechanically isolatable from an environment. The overflow line opens either in a supply path of the cathode supply or in an exhaust path of the cathode supply. The cathode of the fuel cell is fluid-mechanically isolatable from the environment, for example by means of two actuators, in particular two shut-off valves, the cathode supply.

The anode supply and the cathode supply can furthermore be brought into fluid communication with one another by means of a fluid line arranged therebetween and through a valve. The valve is preferably designed as an NC valve, wherein in a de-energized, that is not actuated, state of the NC valve and a balanced pressure ratio at the NC valve, the NC valve is closed. In particular, a closing force of the NC valve is greater than a closing force of the NC relief valve.

In this case, it is assumed that the NC valve and the NC overflow valve are comparable with one another, which relates in particular to the valve seat diameters, flow cross sections, etc. involved. If this is not the case, it must be converted accordingly for a comparability of the two valves. This also preferably means that the NC valve closes and / or closes when there is a pressure difference across the NC valve which is above the critical pressure difference between the anode supply and the cathode supply for the fuel cell.

In this case, the fluid line or the NC valve and the overflow line or the NC overflow valve are preferably connected in parallel. Furthermore, the valve may be located on or in the fluid line. If the overflow line is designed, for example, as a separator line, then the fluid line can be designed as a flushing line. Conversely, the fluid line may be formed, for example, as a separator line, when the overflow is designed as a purge line. Of course, another fluid connection between the anode supply and the cathode supply can also be used for the fluid line or the overflow line.

In embodiments, the NC overflow valve is designed such that at a cathode side lower fluid pressure, a valve member of NC overflow valve, apart from an otherwise acting on the valve member force wegsaugbar or wegdrückbar from its valve seat in NC overflow valve. Furthermore, in the case of an anode-side lower fluid pressure, the valve member, apart from a force that otherwise acts on the valve member, can be sucked or pushed onto its valve seat. Here, the NC overflow valve is preferably designed such that the valve member of an electromagnet is directly or indirectly movable or controllable.

Preferably, the valve member in the direction of its valve seat, ie in particular in the direction of the anode-side fluid pressure, by means of an energy storage device, in particular a (spiral) compression spring, mechanically biased. That is, for opening the valve member of the anode-side fluid pressure must also compensate for a force from the energy storage in addition to the cathode-side fluid pressure (fluid pressure, pressure difference). By means of the energy storage, an anode-side fluid overpressure (with respect to the cathode) is adjustable, from which the NC overflow valve opens and thus establishes the fluid communication between the anode and the cathode. The anode-side fluid overpressure must not exceed the critical pressure difference or should correspond to an uncritical pressure difference (opening overpressure corresponds approximately to closing overpressure).

In the inventive method for supplying or by means of the device according to the invention for supplying an operating medium, in particular hydrogen, from an anode to a cathode of a fuel cell of a Fuel cell system, preferably a vehicle, in particular an electric vehicle, at time and / or time after switching off the fuel cell, is or is a fluid communication through an overflow between an anode supply and a cathode supply of the fuel cell system through active substantially completely prevented or prevented, wherein the fluid communication passively occurs substantially exclusively through a membrane of the fuel cell between the anode supply and the cathode supply.

Under, active 'should be understood here that an actuating means, in particular a valve closes automatically and thus blocks the overflow fluid-mechanically. Furthermore, the anode supply and the cathode supply form an anode-cathode supply device. Prevention of the fluid communication can be done by an NC overflow valve located in / on the overflow line. In this case, the NC overflow valve closes automatically in a de-energized, that is to say a non-controlled state of the NC overflow valve and in the case of a closing pressure difference applied to the NC overflow valve. The closing pressure difference is below or slightly below a critical pressure difference for the fuel cell.

This also means that in the de-energized state of the NC overflow valve and with a balanced pressure ratio at the NC overflow valve, the NC overflow valve is closed. Here again, what has been said about the uncritical and / or critical pressure difference as well as the opening pressure difference (opening overpressure) and / or closing pressure difference (closing overpressure) can be applied to the NC overflow valve. In exemplary embodiments, the overflow line is provided in an anode-cathode supply device according to the invention.

According to the invention results in a combination of a function of an automatic NC overflow valve with an existing valve (purge valve, separator valve, etc.) in the fuel cell system; that is, there are no extra valve, appropriate connections and, if necessary, lines necessary. This can advantageously be dispensed with an NO valve between the anode and the cathode. The invention results in a homogeneous distribution of hydrogen in a fluid-mechanically shut off part of the switched-off fuel cell between an anode and a cathode, wherein no critical pressure differences between the anode and the cathode can occur. Furthermore, problematic air-air starts of the fuel cell are effectively avoided.

An inventive fuel cell system or a vehicle according to the invention have an anode-cathode supply device according to the invention, and / or by the fuel cell system according to the invention or the vehicle according to the invention, a method according to the invention for supplying an operating medium can be carried out. Furthermore, the fuel cell system or the vehicle may have a device according to the invention for supplying the operating medium.

The invention is explained in more detail below with reference to exemplary embodiments with reference to the accompanying schematic drawing. Elements, components or components which have an identical, univocal or analogous design and / or function are provided with the same reference symbols in the description of the figures, the list of reference numerals and the claims and / or are identified by the same reference symbols in the figures of the drawing. Possible, not explained in the description, not shown in the drawing and / or non-exhaustive alternatives, static and / or kinematic reversals, combinations, etc. to the illustrated embodiments of the invention or individual modules, parts or portions thereof, the reference numerals can be found ,

All explained features, including those of the list of reference numerals, are applicable not only in the specified combination or the specified combinations, but also in a different combination or other combinations or in isolation. In particular, it is possible on the basis of the reference symbols and their associated features in the description of the invention, the description of the figures and / or the list of reference numerals, to replace a feature or a plurality of features in the description of the invention and / or the description of the figures. Furthermore, a feature or a plurality of features in the patent claims can thereby be designed, specified and / or substituted. In the figures of the drawing show:

1 a simplified block diagram of a preferred embodiment of a fuel cell system according to the invention;

2 a highly simplified block diagram of an anode-cathode supply device for a fuel cell according to the prior art, with a separator line as an overflow line;

3 a highly simplified block diagram of an anode-cathode power supply device according to the prior art, with a purge line as an overflow line;

4 a highly simplified block diagram of a first embodiment of an anode-cathode supply device according to the invention for a fuel cell, with a separator line as an overflow line;

5 a highly simplified block diagram of a second embodiment of the anode-cathode power supply device according to the invention in turn with a separator line as an overflow line;

6 a highly simplified block diagram of a third embodiment of an anode-cathode power supply device according to the invention, with a purge line as an overflow line;

7 a highly simplified block diagram of a fourth embodiment of an anode-cathode power supply device according to the invention, again with a purge line as an overflow line; and

8th a schematic and centrally sectioned view by an on / in the overflow vorsehbares NC relief valve.

The invention is based on four embodiments of an anode-cathode supply device 20 . 30 for a fuel cell 10 a fuel cell system 1 explained in more detail for a vehicle. Furthermore, the invention is based on a method for feeding or by means of a device 20 . 30 for supplying a working medium 3 , in particular of hydrogen 3 , from an anode to a cathode of the fuel cell 10 temporally at and / or in time after a shutdown of the fuel cell 10 explained in more detail.

However, the invention is not limited to such embodiments and / or the embodiments explained below, but is of a more fundamental nature, so that it applies to all anode-cathode power supplies and methods for supplying or operating medium supply means, for example for stationary fuel cell systems can be. Although the invention has been described and illustrated in detail by preferred embodiments, the invention is not limited by the disclosed embodiments. Other variations can be deduced therefrom without departing from the scope of the invention.

The 1 shows a fuel cell system 1 according to a preferred embodiment of the invention. The fuel cell system 1 is preferably part of a vehicle not shown in detail, in particular a motor vehicle or an electric vehicle, which preferably has an electric traction motor, which or by the fuel cell system 1 can be supplied with electrical energy.

The fuel cell system 1 includes as a core component a fuel cell 10 or a fuel cell stack 10 , Which or which a plurality of stacked fuel cells (hereinafter referred to as single cells 11 designated). Every single cell 11 includes an anode compartment 12 and a cathode compartment 13 , which preferably of an ion-conductive polymer electrolyte membrane 14 spatially and electrically separated from each other (see detail of the 1 ). The fuel cell stack 10 is also easy as a fuel cell 10 designated.

The anode rooms 12 and the cathode rooms 13 each have a catalytic electrode (both not shown), that is, an anode and a cathode, each catalyzing a partial reaction of a fuel cell reaction. The anode electrode and the cathode electrode each comprise a catalytic material, such as platinum, supported on an electrically conductive substrate having a large surface area, such as a carbon-based material.

A structure of a membrane 14 and electrodes is also called a membrane-electrode unit 11 designated. Between two such membrane-electrode units 11 is also each an indicated bipolar plate 15 arranged, which a supply of operating media in the anode chambers 12 and the cathode rooms 13 serves and beyond an electrical connection between the individual cells 11 realized.

To supply the fuel cell stack 10 or the fuel cell 10 with the operating media 3 . 5 has the fuel cell system 1 on the one hand, an anode supply 20 and on the other hand, a cathode supply 30 on.

The anode supply 20 includes an anode supply path 21 , which is a supply of an anode operating medium 3 , a fuel 3 , for example hydrogen 3 or a hydrogen-containing gas mixture 3 , in the anode rooms 12 the fuel cell 10 serves. For this purpose, the anode supply path connects 21 a fuel storage 23 or fuel tank 23 with an anode inlet of the fuel cell 10 , The anode supply 20 further comprises an anode exhaust path 22 , which is an anode exhaust 4 from the anode chambers 12 through an anode outlet of the fuel cell 10 through. An established anode operating pressure on the anode side of the fuel cell 10 is preferably by means of an actuating means 24 in the anode supply path 21 adjustable.

In addition, the anode supply points 20 preferably a fuel recirculation line 25 on which the anode exhaust path 22 with the anode supply path 21 fluid mechanically connects. A recirculation of the anode operating medium 3 , that is, the actually preferred fuel to be refueled, is often set up, the most over-stoichiometric anode operating medium 3 the fuel cell 10 to be returned and used. In the fuel recirculation line 25 is preferably a further adjusting agent 26 arranged, with which a recirculation rate is adjustable. Further, additionally or alternatively, in the fuel recirculation line 25 a compressor 28 (see the 4 to 7 ) be provided.

The cathode supply 30 includes a cathode supply path 31 which is the cathode spaces 13 the fuel cell 10 an oxygen-containing cathode operating medium 5 , preferably air 5 , feeds, which in particular from the environment 2 is sucked. The cathode supply 30 further includes a cathode exhaust path 32 , which is a cathode exhaust 6 , in particular an exhaust air 6 , from the cathode rooms 13 the fuel cell 10 dissipates and optionally this an exhaust system (not shown) supplies.

For a promotion and compression of the cathode operating medium 5 is in the cathode supply path 31 preferably a compressor 33 arranged. In the illustrated embodiment, the compressor 33 as a possibly mainly electric motor driven compressor 33 designed, the drive by means of an electric motor 34 or a drive 34 takes place, preferably with a corresponding power electronics 35 Is provided. The compressor is preferred 33 as an electric turbocharger (English ETC for Electric Turbo Charger) formed. The compressor 33 can also be characterized by a in the cathode exhaust path 32 arranged turbine 36 with optional variable turbine geometry supportive means of a common shaft (not shown) are driven. The turbine 36 represents an expander, which is an expansion of the cathode exhaust gas 6 and thus causes a lowering of the fluid pressure.

The cathode supply 30 may also according to the illustrated embodiment, a wastegate 37 or a wastegate line 37 which or which the cathode supply path 31 or a cathode supply line with the cathode exhaust path 32 or a cathode exhaust pipe connects, so a bypass for the fuel cell 10 represents. The wastegate 37 allows an operating pressure of the cathode operating medium 5 short term in the fuel cell 10 reduce without the compressor 33 shut down. One in the wastegate 37 arranged adjusting means 38 allows adjustment of a volume flow of the fuel cell 10 immediate cathode operating medium 5 ,

All adjusting means 24 . 26 . 38 . 310 . 320 . 400 (see also below) of the fuel cell system 1 can be designed as controllable, controllable or non-controllable valves, flaps, throttles, etc. For further isolation (see the 4 to 7 ) of the fuel cell 10 from the surroundings 2 can at least one corresponding further actuating means 310 . 320 in a path 21 . 22 . 31 . 32 or a line of the path 21 . 22 . 31 . 32 be arranged.

The preferred fuel cell system 1 also has a humidifier module 39 on. The humidifier module 39 On the one hand, this is the case in the cathode supply path 31 arranged it from the cathode operating medium 5 can be flowed through. On the other hand, the humidifier module 39 such in the cathode exhaust path 32 arranged it from the cathode exhaust 6 can be flowed through. The humidifier module 39 is on the one hand in the cathode supply path 31 preferably between the compressor 33 and a cathode input and, on the other hand, the cathode exhaust path 32 between the turbine 36 and a cathode output of the fuel cell 10 arranged. A humidifier of the humidifier module 39 typically has a plurality of water vapor permeable membranes, which are often formed either flat or in the form of hollow fibers.

Various other details of the fuel cell system 1 or the fuel cell 10 / of the fuel cell stack 10 , the anode supply 20 and the cathode supply 30 are in the simplified 1 not shown for reasons of clarity. So the humidifier module 39 both from the cathode supply path 31 as well as from the cathode exhaust path 32 be bypassed by means of a bypass line. There may also be a turbine bypass line from the cathode exhaust path 32 be provided, which is the turbine 36 bypasses.

Further, in the anode exhaust path 22 and / or in the cathode exhaust path 32 a water separator 27 (in the 4 to 7 this is for the anode exhaust path 22 shown), by means of which a from the relevant partial reaction of the fuel cell 10 resulting product water condensable and / or separable and in a Water collector is derivable. Furthermore, the anode supply 20 alternatively or additionally to the cathode supply 30 have similar humidifier module. Furthermore, the anode exhaust path 22 in the cathode exhaust path 32 (see the 4 to 7 ) or vice versa, so that the anode exhaust 4 and the cathode off-gas 6 can be removed via a common exhaust system.

When switching off the fuel cell 10 becomes the cathode or the cathode chambers by means of adjusting means 310 . 320 , in particular shut-off valves 310 . 320 in the cathode supply path 31 and in the cathode exhaust path 32 from the surroundings 2 isolated. During and after isolation, the anode or the anode chambers have a higher fluid pressure than the cathode or the cathode chambers. The anode supply 20 and the cathode supply 30 are also by means of a separator line 100 and / or a purge line 200 fluidmechanically connectable. Preferably, the separator line extends 100 from the water separator 27 the anode supply 20 to the cathode supply 30 , Furthermore, the purge line extends 200 also from the anode supply 20 to the cathode supply 30 ,

The separator line 100 flows preferentially in the anode exhaust path 22 ( 4 to 7 ). Here, the separator line 100 with respect to a fluid circuit in the anode supply 20 upstream ( 4 and 5 ) or downstream ( 6 and 7 ) of the purge line 200 in the anode supply 20 lead. Furthermore, the separator line 100 in a fluidmechanisch lockable part of the cathode supply 30 in the cathode exhaust path 32 , ie upstream of the (considered open) shut-off valve 320 ( 4 ), or in the cathode supply path 31 , that is downstream of the (designed as open) shut-off valve 310 ( 5 ). In addition, the separator line 100 downstream of the fluid-mechanically shut-off part of the cathode supply 30 , ie downstream of the shut-off valve 320 ( 6 and 7 ), in the cathode exhaust path 32 lead.

The flushing line 200 also preferably flows in the anode exhaust path 22 ( 4 to 7 ). Here, the purge line 200 with respect to the fluid circuit in the anode supply 20 downstream ( 4 and 5 ) or upstream ( 6 and 7 ) of the water separator 27 or the separator line 100 into the anode supply 20 lead. Furthermore, the purge line 200 in the fluid-mechanically shut-off part of the cathode supply 30 in the cathode exhaust path 32 , ie upstream of the (considered open) shut-off valve 320 ( 6 ), or in the cathode supply path 31 , that is downstream of the (designed as open) shut-off valve 310 ( 7 ). In addition, the purge line can 200 downstream of the fluid-mechanically shut-off part of the cathode supply 30 , ie downstream of the shut-off valve 320 ( 4 and 5 ), in the cathode exhaust path 32 lead.

According to the invention, one of the fluid lines 100 . 200 between the anode supply 20 and the cathode supply 30 as an overflow line 100 . 200 educated. Depending on which of the fluid lines 100 . 200 as overflow line 100 . 200 is formed, the overflow can 100 . 200 as a separator line 100 , a flush pipe 200 , a fluid line, etc. may be formed. Here is on / in the overflow line 100 . 200 an overflow valve 400 intended. Is the overflow valve 400 for example, on / in the separator line 100 provided, so the spill valve 400 as a separator valve 400 be educated. Is the overflow valve 400 however, on / in the flushing line 200 provided, so the spill valve 400 as a purge valve 400 or a purge valve 400 be educated. And in the optionally applied fluid line is the overflow valve 400 designed as a fluid valve.

According to the invention, the overflow valve 400 , with which a pressure equalization between the anode and the cathode is ensured, as an NC valve formed NC overflow valve 400 educated. NC stands for Normally Closed; that is, the overflow valve 400 is closed, if it is not energized or not driven. Furthermore, the NC overflow valve 400 designed such that when flared fuel cell 10 a critical overpressure or a critical pressure difference between the anode and the cathode can be avoided, since the NC overflow valve 400 before reaching this pressure difference opens and a fluid communication between the anode supply 20 and the shut off part of the cathode supply 30 manufactures. The cathode is by means of the shut-off valves 310 . 320 from the surroundings 2 fluid mechanically isolated.

There is no further, direct fluid connection, for example via an NO valve, for the pressure equalization between the anode and the cathode as in the prior art. By using the NC overflow valve 400 between the anode and the cathode, it is possible that an anode-side fluid pressure p ₁ (see 8th ) over a cathode-side fluid pressure p ₂ (see 8th ) is in the vehicle is switched off. Thus, in comparison with the prior art, a larger volume of hydrogen remains 3 in the anode supply 20 , An anode-side overpressure p ₁ - p ₂ in the fuel cell system 1 will be over the membrane with a time 14 (actually the membranes 14 ) of the fuel cell 10 Degrade and evenly in the fuel cell stack 10 to distribute. As a result, the air present on the cathode after switching off the fuel cell 10 evenly mined.

The NC overflow valve 400 between the anode and through the shut-off valves 310 . 320 completed cathode may be formed differently and different positions in the anode-cathode power supply 20 . 30 own, which have different advantages. In particular, the NC overflow valve 400 as a separator valve 400 or as a flush valve 400 or purge valve 400 educated. Here, the NC overflow valve 400 connect an anode inlet or an anode outlet with a cathode inlet or a cathode outlet.

According to the invention, the NC overflow valve 400 designed such that the NC overflow valve 400 from a certain pressure difference on the NC overflow valve 400 is pressed by this pressure difference. This pressure difference should be less than a maximum permanently permissible pressure difference between the anode and the cathode. The NC overflow valve 400 can be designed such that the operating medium 3 , ie in particular hydrogen 3 , against a valve seat 422 of the NC overflow valve 400 flows on (see 8th ). In the NC overflow valve 400 then a compressive force acts from the operating medium 3 due to the pressure difference at the NC overflow valve 400 , against an energy store 430 of the NC overflow valve 400 , which has a permanent tendency, the NC overflow valve 400 zuzudrücken. If the pressure force, ie a pressure difference at the NC overflow valve 400 , greater than the power from the energy store 430 becomes, so will the NC overflow valve 400 pressed.

The 8th shows an example of such a usable NC valve concept for the NC overflow valve according to the invention 400 , On average, the 8th is a valve body 420 and a linearly movably received therein valve member 410 to see. The valve member 410 is by means of one in the valve body 420 absorbed electromagnet 440 depending on a control of the electromagnet 440 from his valve seat 422 in the valve body 420 wegbewegbar, wherein the valve member 410 at the energy storage 430 , in particular a (spiral) compression spring 430 , in the valve body 420 supported. Other NC valve concepts are of course applicable.

Depending on a control of the electromagnet 440 , a (pressure) force of the energy storage 430 and the pressure conditions in the anode supply 20 (p ₁ ) and the cathode supply 30 (p ₂ ) is the NC overflow valve 400 closed, opens the NC overflow valve 400 , is the NC overflow valve 400 open, closes the NC overflow valve 400 or is the NC overflow valve 400 closed (operation of the fuel cell 10 ). Will the electromagnet 440 not activated, so a state of the NC overflow valve depends 400 only by the power of the energy storage 430 and the pressure conditions in the anode supply 20 (p ₁ ) and the cathode supply 30 (p ₂ ) from (switched off state of the fuel cell 10 , if necessary, operation of the fuel cell 10 ).

This opens (p ₁ > p ₂ ) the NC overflow valve 400 from a certain anode-side, relative fluid (over) pressure p ₁ with respect to a cathode-side relative fluid (under) pressure p ₂ , ie at a certain pressure difference p ₁ - p ₂ (opening pressure difference, opening pressure). With this pressure difference p ₁ - p ₂ is at a given geometry of the NC overflow valve 400 the power of the energy storage 430 surmountable, the NC overflow valve 400 opens. In the present case, this pressure difference p ₁ -p ₂ is smaller than the critical pressure difference between the anode and the cathode of the fuel cell 10 , If the anode-side, relative fluid (over) pressure drops p ₁ , so that the specific pressure difference p ₁ - p ₂ (closing pressure difference, closing pressure) is exceeded, so closes the NC overflow valve 400 sure again.

Parallel to the NC overflow valve 400 is preferred in the respective other fluid line 100 . 200 as a separator valve 500 , Flush valve 500 etc. trained valve 500 is provided, which preferably also as an NC valve 500 is trained. Here is a closing force of the NC valve 500 preferably greater than a closing force of the NC relief valve 400 designed, of course, only on comparable valves 400 . 500 true. If necessary, that is for non-comparable valves 400 . 500 , needs a comparable base for both valves 400 . 500 being found.

LIST OF REFERENCE NUMBERS

1

Fuel cell system, preferably for a vehicle with an electric motor, in particular an electric traction motor

2

Surroundings

3

Operating medium, reactant, in particular anode operating medium, actual fuel, preferably hydrogen or hydrogen-containing gas mixture

4

Exhaust gas including liquid water, in particular anode exhaust gas

5

Operating medium, reactant, in particular cathode operating medium, preferably air

6

Exhaust gas including liquid water, in particular cathode exhaust gas, preferably exhaust air

7

Coolant, especially water, water-alcohol mixture, water-ethylene glycol mixture

10

Fuel cell, fuel cell stack

11

Single cell with anode and cathode, single fuel cell

12

anode chamber

13

cathode space

14

Membrane, preferably polymer electrolyte membrane

15

Bipolar plate, flow field plate

20

Anode supply, anode circuit of the fuel cell 10 or the fuel cell stack 10

21

Path, supply path, flow path, anode supply path

22

Path, exhaust path, flow path, anode exhaust path

23

Fuel storage, fuel tank with anode operating medium 3

24

Adjusting means, controllable, (on) controllable, not adjustable, in particular valve, flap, throttle etc.

25

Fuel recirculation line

26

Adjusting means, controllable, (on) controllable, not adjustable, in particular valve, flap, throttle etc.

27

water

28

compressor

30

Cathode supply, cathode circuit of the fuel cell 10 or the fuel cell stack 10

31

Path, supply path, flow path, cathode supply path

32

Path, exhaust path, flow path, cathode exhaust path

33

Compressor, compressor, turbocharger

34

Motor, in particular electric motor or drive (if necessary including gear)

35

Electronics, in particular power electronics for the motor 34

36

Turbine with possibly variable turbine geometry, expander

37

Wastegate, Wastegate pipe

38

Adjusting means, controllable, (on) controllable, not adjustable, in particular valve, flap, throttle etc.

39

Humidifier, humidifier module

100

Overflow line, separator line / fluid line

200

Overflow line, purge line / fluid line

310

Adjusting means, adjustable, (on) controllable, not adjustable, in particular shut-off valve

320

Adjusting means, adjustable, (on) controllable, not adjustable, in particular shut-off valve

400

Adjusting means, controllable, (on) controllable, not controllable, in particular overflow valve, NC overflow valve preferably designed as a fluid valve, gas valve, separator valve, purge valve (purge valve)

401

NO overflow valve (state of the art only)

410

valve member

420

valve body

422

valve seat

430

Energy storage, in particular (spiral) compression spring

440

electromagnet

500

Adjusting means, controllable, (controllable), not controllable, in particular valve, NC valve

p ₁

Fluid pressure, anode-side fluid pressure, in particular on the valve member 410

p ₂

Fluid pressure, cathode-side fluid pressure, in particular on the valve member 410

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006035851 B4 [0010]

Claims (10)

Anode-cathode supply device ( 20 . 30 ) for a fuel cell ( 10 ) of a fuel cell system ( 1 ) with an anode supply ( 20 ) and a cathode supply ( 30 ), which by means of an interposed overflow line ( 100 / 200 / ...) and by an overflow valve ( 400 ) can be brought together in a fluid communication, characterized in that the overflow valve ( 400 ) as an NC overflow valve ( 400 ) is formed, wherein in a de-energized state of the NC overflow valve ( 400 ) and with a balanced pressure ratio at the NC overflow valve ( 400 ) the NC overflow valve ( 400 ) closed is. Anode-cathode supply device ( 20 . 30 ) according to claim 1, characterized in that the NC overflow valve ( 400 ) is designed such that the NC overflow valve ( 400 ) at a pressure difference at the NC overflow valve ( 400 ), which below one for the fuel cell ( 10 ) critical pressure difference (p ₁ -p ₂ , p ₂ -p ₁ ) between the anode supply ( 20 ) and the cathode supply ( 30 ) lies. Anode-cathode supply device ( 20 . 30 ) according to claim 1 or 2, characterized in that the NC overflow valve ( 400 ) is designed such that the NC overflow valve ( 400 ) opens at an anode-side fluid pressure (p ₁ ) which is above a cathode-side fluid pressure (p ₂ ), wherein a pressure difference (p ₁ - p ₂ ) between the anode-side fluid pressure (p ₁ ) and the cathode-side fluid pressure (p ₂ ) below critical pressure difference for the fuel cell ( 10 ) lies. Anode-cathode supply device ( 20 . 30 ) according to one of claims 1 to 3, characterized in that the overflow line ( 100 / 200 / ...) furthermore as a separator line ( 100 ), a purge line ( 200 ) or another line is formed, wherein the overflow line ( 100 / 200 / ...) in the anode supply ( 20 ) and in the cathode supply ( 30 ) opens. Anode-cathode supply device ( 20 . 30 ) according to one of claims 1 to 4, characterized in that the overflow line ( 100 / 200 / ...) within one of an environment ( 2 ) fluid-mechanically isolatable region of the cathode supply ( 30 ) into the cathode supply ( 30 ), wherein the overflow line ( 100 / 200 / ...) either in a supply path ( 31 ) of the cathode supply ( 30 ) or in an exhaust path ( 32 ) of the cathode supply ( 30 ) opens. Anode-cathode supply device ( 20 . 30 ) according to one of claims 1 to 5, characterized in that the anode supply ( 20 ) and the cathode supply ( 30 ), further by means of an interposed fluid line ( 200 / 100 / ...) and through a valve ( 500 ) can be brought together in a fluid communication, and the valve ( 500 ) as an NC valve ( 500 ) is formed, wherein in a de-energized state of the NC valve ( 500 ) and with a balanced pressure ratio at the NC valve ( 500 ), the NC valve ( 500 ) is closed, and a closing force of the NC valve ( 500 ) in particular greater than a closing force of the NC overflow valve ( 500 ). Anode-cathode supply device ( 20 . 30 ) according to one of claims 1 to 6, characterized in that the NC overflow valve ( 400 ) is designed such that at a cathode side (p ₂ ) lower fluid pressure (p ₂ <p ₁ ), a valve member ( 410 ) of the NC relief valve ( 400 ), apart from another on the valve member ( 410 ) acting force, from its valve seat ( 422 ) in the NC overflow valve ( 400 ) is sucked away, and / or at an anode side (p ₁ ) lower fluid pressure (p ₂ > p ₁ ), the valve member ( 410 ), apart from another on the valve member ( 410 ) acting force, on its valve seat ( 422 ) is sucked. Method for supplying an operating medium ( 3 ), in particular of hydrogen ( 3 ), from an anode to a cathode of a fuel cell ( 10 ) of a fuel cell system ( 1 ) temporally at and / or after a shutdown of the fuel cell ( 10 ), characterized in that a fluid communication through an overflow ( 100 / 200 / ...) between an anode supply ( 20 ) and a cathode supply ( 30 ) of the fuel cell system ( 1 ) is substantially completely prevented, whereby the fluid communication between the anode supply ( 20 ) and the cathode supply ( 30 ) essentially exclusively by a membrane ( 14 ) of the fuel cell ( 10 ) through. A method according to claim 8, characterized in that prevention of fluid communication by a in / at the overflow ( 100 / 200 / ...) NC overflow valve ( 400 ), wherein in a de-energized state of the NC overflow valve ( 400 ) and one at the NC overflow valve ( 400 ) applied closing pressure difference, the NC overflow valve ( 400 ) closes automatically, wherein the closing pressure difference is slightly below a critical pressure difference for the fuel cell ( 10 ), and / or the overflow line ( 100 / 200 / ...) in an anode-cathode supply device ( 20 . 30 ) is provided, which is designed according to one of claims 1 to 7. Fuel cell system ( 1 ) for a vehicle, in particular an electric vehicle, or Vehicle, in particular electric vehicle, characterized in that the fuel cell system ( 1 ) or the vehicle has an anode-cathode supply device ( 20 . 30 ) according to one of claims 1 to 7, and / or by the fuel cell system ( 1 ) or the vehicle, a method for supplying an operating medium ( 3 ) according to claim 8 or 9 is feasible.

Images